Medics helped develop a "WhatsApp Doc" messaging service to enable hospital doctors to securely contact colleagues with questions about patient care.
St George's Hospital in south-west London said it has become the first hospital in the UK to launch the secure messaging app Medxnote for staff to exchange confidential patient information and photos.
Hundreds of staff are now using the app, the hospital said.
A spokeswoman added that the app, which can be used on iOS or Android smartphones, had the familiar look and feel of the popular app WhatsApp.
Medxnote, created in partnership with a tech firm of the same name, allows staff to communicate quickly but it complies with data protection and patient confidentiality guidelines, St George's University Hospitals NHS Foundation Trust said.
Data from the app is not saved anywhere else on the phone and is solely stored in the app - which can't be accessed without logging in with a verified account.
The news comes after reports clinicians were using Snapchat and other messaging services to exchange information quickly.
This prompted concerns over the use of some apps and strict patient confidentiality rules.
Earlier this year, an independent panel appointed to examine the dealings that Google's DeepMind Health has with the NHS concluded that the health service had let the digital revolution pass it by.
As a result, medics are performing their own "technical fixes" including using SnapChat to send patient scans to each other. This is an "insecure, risky and non-auditable way of operating", the report's authors said.
Dr Sarah Hammond, consultant anaesthetist at St George's, who helped with the development of the app, said: "This has the potential to be a real game-changer for clinicians working in the NHS, so we are delighted to be the first trust to launch it.
"The new app provides staff at St George's with a secure, easy-to-use platform to communicate and help them provide the best possible care for our patients."
She told the Press Association: "Email is the most common form of communication which isn't particularly timely or practical for clinicians as they're not based at computers and need to communicate quickly with one another.
"Being able to do so in a safe and secure way via this smartphone app has improved how we communicate - especially with colleagues based in different departments and sites.
"It's really reassuring to know that you can take photos in the app and it won't be stored anywhere else on your phone so we can take images securely knowing that it's on a highly encrypted network."